shroomverse

GLOSSARY · CHEMISTRY AND THE BODY

Blood-brain barrier

Also called: BBB, blood–brain barrier

The tightly sealed lining of the brain’s blood vessels, which lets some molecules into the brain and keeps others out. It helps explain why some mushroom and toad compounds seem to do little when injected.

The blood-brain barrier is the filter between the bloodstream and the brain, formed by the tightly joined cells lining the brain’s blood vessels. Small, fat-soluble molecules tend to cross it; charged or strongly water-loving ones often do not. Whether a compound crosses is one of the first questions researchers ask about any new psychoactive candidate.

It turns up in mushroom chemistry. A 2025 rat study found that baeocystin and norpsilocin had a very limited ability to cross the barrier, and baeocystin had no significant behavioural effects (Danda et al., 2025). For bufotenine, a 2000 review argued that poor passage across the blood-brain barrier best explains its weak effects in human experiments, despite activity at psychedelic receptors (McBride, 2000).

DMT, by contrast, crosses cell membranes easily, a property a 2023 study used to show it can reach serotonin receptors inside neurons (Vargas et al., 2023). Barrier data mostly come from animals and cell models, so how much of a given compound reaches the living human brain is usually unknown.

Sources

Last checked .